Conventionally, an access control list (ACL) is used to allow only those devices (such as personal computers) used by specific members belonging to a certain group to access the network resources and prevent unauthorized accesses from third parties. Using the access control list, connection requests from users or devices not listed on the access control list are rejected to prevent unauthorized accesses.
In a wireless LAN, access control called MAC (media access control) address filtering is performed using an access control list. Multiple access points (APs) share the access control list to exclude unauthorized accesses from devices with MAC addresses not listed in the access control lists.
However, there are problems arising in simply using an access control list to prevent unauthorized accesses from third parties.
With the conventional access control technique using an access control list, each of the access points checks accesses using the access control list at each location as long as such accesses are made through this accessing route. However, this technique cannot be applied to an ad-hoc environment in which direct connection and/or resource sharing is carried out among multiple devices. For example, members of a particular group may connect their devices directly with each other to mutually exchange information, or a mesh network may be structured using home digital devices to share resources through mutual connections. In such a situation, a device being accessed cannot specify in advance the counterpart device currently accessing the former device, and therefore, it is difficult to prevent spoofing by a malicious third party. This involves the risk of leak of confidential information intended to be opened only to the group member.
In addition, when an access check mechanism using an ACL is provided to an accessing route, an administrator has to update the access control list every time a new user or a new device is added. Workload increases, while prompt response cannot be expected. This problem becomes conspicuous especially when forming a mesh network. One of the advantages of a mesh network is broadening of coverage by participation of multiple devices. In order to take advantage of this feature, multiple participants have to be allowed to freely connect their devices to the mesh network. It is difficult for the conventional technique to realize this, while maintaining network security.